Elucidating the trafficking mechanisms of effector proteins to the Plasmodium infected red blood cell

项目摘要 恶性疟原虫是一种致命的人类寄生虫，导致疟疾， 每年死亡。疟疾是世界上大部分地区的地方病，约有40亿人居住， 每年影响约2.5亿人。目前还没有有效的疟疾疫苗和抗疟疾药物 是治疗的主要手段。在这个时候，寄生虫已经获得了抵抗所有临床可用 抗疟疾药物和这些耐药菌株正在世界各地蔓延，威胁着所有 在过去十年里，在防治这一疾病方面取得了进展。因此，我们必须 不断开发新的药物并确定潜在的药物靶点，以领先于这种邪恶的疾病。的 这种毁灭性的寄生虫病的临床表现，包括死亡，是由P. 恶性疟原虫在宿主红细胞（RBC）内。为了在红细胞内建立一个合适的生长环境， 寄生虫会完全转化宿主细胞它改变了红细胞的新陈代谢，使红细胞更坚硬 使受感染的红细胞更难通过毛细血管，改变红细胞膜， 有利的营养物质的运动，并改变红细胞的结合特性，使受感染的细胞可以结合 到血管内皮细胞。这些变化的总和导致疾病和死亡，因为 例如，恶性疟原虫感染的红细胞与内皮细胞的结合可阻塞脑血管 导致血栓最终导致死亡受感染的红细胞的征服是通过 寄生虫通过人们知之甚少的方式将数百种蛋白质转运到宿主细胞的作用 机制等寄生虫效应蛋白的输出对于转化RBC是必不可少的，因此， 导致疾病。在寄生虫细胞质中合成的寄生虫效应蛋白需要被 通过三个或四个细胞膜运输，以到达其在宿主RBC中的作用位点。的 识别、分类和运输这些寄生虫效应物到受感染红细胞的分子机制仍然存在， 待鉴定拟议的研究旨在揭示控制关键早期事件的分子过程， 在通往宿主红细胞的路径上设置寄生虫效应器。为了实现这一目标，我们将追求两个目标。一是 将在寄生虫的内质网中产生蛋白质的条件突变体， 出口寄生虫效应器所需的。突变体将通过遗传细胞和生物化学方法进行分析 方法来确定它们在寄生虫蛋白质输出中的作用。第二，我们将采取公正的 相互作用组筛选方法，其使用基于邻近的标记方法并发现 usher将蛋白质输出到它们在宿主RBC中的作用位点。实现研究计划的目标 将揭示恶性疟原虫的关键和独特的蛋白质运输机制， 药物开发

Project Summary Plasmodium falciparum is a deadly human parasite that causes malaria and is responsible for nearly 450,000 deaths every year. Malaria is endemic in large regions of the world, home to about 4 billion people and it affects ~250 million people annually. There are no effective vaccines against malaria and antimalarial drugs are the mainstay of treatment. At this time, the parasite has gained resistance to all clinically available antimalarial drugs and these drug-resistant strains are spreading throughout the world, threatening all the progress that has been made against this disease in the last decade. Therefore, it is imperative that we constantly generate new drugs and identify potential drug targets to stay ahead of this nefarious disease. The clinical manifestations of this devastating parasitic disease, including death, are caused by the growth of P. falciparum within the host red blood cell (RBC). To build a suitable habitat for growth inside RBCs, the malaria parasite completely transforms the host cell. It changes the metabolism of the RBC, makes the RBC more rigid such that it is harder for the infected RBC to pass through capillaries, modifies the RBC membrane to allow for favorable movement of nutrients, and alters the binding properties of the RBC so that the infected cell can bind to the endothelial cells lining blood vessels. The sum of these changes leads to disease and death, for instance, binding of the P. falciparum infected RBC to endothelial cells can clog blood vessels in the brain leading to clots that eventually result in death. The subjugation of the infected RBC is accomplished through the action of several hundred proteins that the parasite transports to the host cell via poorly understood mechanisms. The export of parasite effector proteins is essential for transforming the RBC and therefore, for causing disease. Parasite effector proteins that are synthesized in the parasite cytoplasm need to be transported across three or four cellular membranes in order to reach their site of action in the host RBC. The molecular mechanisms that recognize, sort, and transport these parasite effectors to the infected RBC remain to be identified. The proposed studies aim to unravel the molecular processes that govern key early events that set parasite effectors on the path to the host RBC. We will pursue two aims to accomplish this goal. First, we will generate conditional mutants of proteins in the endoplasmic reticulum of the parasite that are potentially required for export of parasite effectors. The mutants will be analyzed using genetic, cellular, and biochemical approaches to determine their roles in the export of parasite proteins. Second, we will take an unbiased interactome screening approach that uses a proximity-based labeling approach and discover proteins that usher exported proteins to their site of action in the host RBC. Attaining the objectives of the research program will reveal key and unique protein trafficking mechanisms of P. falciparum that may be targeted for antimalarial drug development.